Heat exchange element and process of making same



April 9, 1940. A. .1. BERG ET AL 2,196,186

HEAT EXCHANGE ELEMENT AND PROCESS OF MAKING SAME Filed Feb. 14, 1936 3 Sheets-Sheet 1.

ATTORNEYS.

April 9, 1940. A. J. BERG ET AL 2,196,136

EMENT AND YROCESS 0F IAKING SAME ulm wmwwmmw WWI TTTTTT EY April 9, 1940. A. .1. BERG El AL 2,196,186

HEAT EXCHANGE ELEMENT AND PROCESS OF MAKING SAME Filed Feb. 14. 1936 3 Sheets-Sheet 3 IN a o J. 19:22: BY Jay/v O. #0.:

ATTORNEY Patented Apr. 9, 1940 UNITED STATES PATENT OFFICE Alfred J. Berg, Portsmouth, N. 11., and John 0. Huse, United States Navy Application February 14, 1936, Serial No. 83,89!

6 Claims.

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) This invention relates to a new and useful heat and cold exchanging element and method 'of making the same, and has for its object the Other objects of this invention will become apparent, at least to those skilled in this art,

from the following specification together with the advantages, inherent and otherwise, of this invention in its several related aspects of article and method.

Heretofore, heat and cold exchanging elements have been constructed with the body portion, which is most frequently of a hollow or tubular article, having its wall thicker and heavier than would be required to resist the pressure and corrosion or other deteriorating action, to which the same is required to be subjected in use. Such thicker, heavier wall is required to be employed in order that the same may be provided with grooves or other means for-mounting thereon and securing thereto the projecting ribs or fins which are required to increase the rate of exchange of heat and cold to and from the body wall.

The present invention employs a substantially thinner, lighter body wall of no more strength than required to resist the action thereon of the forces and agencies encountered in use, without disturbing the exterior surface or otherwise impairing the body wall. Inthe execution of this concept, the heat and cold exchanging ribs or fins are mounted upon and secured to the virgin surface of the body wall without impairment of any of the characteristics of such body wall; and the form, arrangement, means for securing the parts together, as well as the method of making the same, have been devised and employed in furtherance of said concept.

In the drawings:

Fig. 1 is an end view, partially in perspective, diagrammatically illustrating one means for making the ribs or fins in accordance with my invention;

Fig. 2 is a top plan view of the parts shown in Fig. 1;

Fig. 3 is a perspective view of a number of such ribs or fins which may be made by the apparatus shown in Figs. 1 and 2;

Fig. 4 is a perspective view of a row of ribs or fins which may be diiferently produced;

Fig. 5 is a top plan view of a portion of a heat 5 exchanger body or tube having mounted thereon in separated rows the ribs or fins disclosed in Fig. 3;

Fig. 6 is an end view with the body or tube in cross section, of the parts shown in Fig. 5;

Fig. '7 is a view similar to Fig. 5 but illustrating the ribs or fins applied helically about the body portion;

Fig. 8 is a view similar to Fig. 5 but illustrating the ribs or fins of Fig. 4 applied to the body por- 15 tion in separated rows or rings;

Fig. 9 is an end elevation view of the parts shown in Fig. 8 with the body or tube in cross section;

Fig. 10 is a top plan view similar to Fig. 7 but 20 employing the ribs or fins of Fig. 4;

Fig. 11 is a top plan view of a portion of a row of ribs or fins constructed in accordance with Fig. 3;

Fig. 12 is a top plan view of a portion of a row 25, of ribs or fins constructed in accordance with Fig. 4;

Figs. 13 and 14 are perspective views of differently shaped ribs or fins;

Fig. 15 is a top plan view of a portion of a heat exchanger body or tube having helically coiled thereabout a portion of a row of ribs or fins constructed in accordance with Figs. 13 and 14; and

Fig. 16 is an end elevational view of the parts shown in Fig. 15.

In the drawings, in which like characters of reference indicate the same parts, in is a preferably rectangular tube of copper or other metal, which is slidably mounted and supported at least upon its opposite sides and lower surface by a guide not illustrated; II is a rock shaft having secured thereto radially extending knife bars i2, angularly spaced apart and having cutting edges l3 facing each other, the distance between edges l3 exceeding the width of the tube l0, as indicated by the dotted lines representing knives l2 on opposite sides of tube l0 shown in Fig. 1. When shaft II is rocked, one of the .cutting edges iii of knife l2 will commence to make a shearing cut on the adjacent corner of tube H), which cut will be continued through the tube l0 and terminate when the edge l3 of such knife I2 is substantially parallel with the inner surface of the opposite vertical wall of tube l0. 'I'hereupon such knife I! will retreat from such cut and 66 come momentarily to rest. During such rest period the tube III is longitudinally moved further toward the plane in which the knife edges '3 lie, said movement being for a distance represented by the required thickness of the individual rib or fin Il to be formed by each such cut I of a knife I2. whereupon tube II is held in fixed position on its said supports while the opposite knife I 2 is making a similar cut in the opposite direction in tube I0. These cutti spacing, and holding operations are repeated and the requisite length of a row of the thus severed ribs or fins II is formed. The means for spacing and holding the tube II, as well as for rocking the shaft II, are not shown in the drawings as the same may be performed by hand or by a number of existing apparatus with or without substantial modification, as those skilled in the art will readily understand herefrom. These opposite cuts in tube III are more fully shown in Figs. 3 and 11, and such cuts may be made by hand, by a hack saw, a knife or other cutter. We prefer not to make such cuts with a saw for the economical reason that the saw wastes the metal of the tube I comprised in the area of the saw out, while the knife or shear cut does not waste any of the metal of tube II, and the knife out has the additional slight advantage of expanding and separating the alternate severed sides from each of the separate ribs or fins Il thus formed, as indicated at the right end of Fig. 11.

The row of ribs Ila of Fig. 4 is formed by helically coiling or winding about an oblong form a thin relatively narrow strip of metal of rectangular cross section. This produces a hollow rectangular helically shaped tube similar to that differently produced by the structure of Fig. 3.

In Figs. 13 and 14 we have illustrated the formation of a row of ribsor fins I lb resulting from the helical coiling of a flat, thinl relatively narrow ribbon of metal wound edgewise about a central forming member which may be round. In Fig. 14 one edge of each of the ribs or fins llb comprising the helical coil has been flattened at I5 preferably by the severance of metal from each of the ribs or fins llb comprising thehelical coil.

The row of connected ribs or fins ll of Fig. 3, or Ila of Fig. 4, or Ilb of Figs. 13 and 14 may be secured at one end by solder or otherwise to the body It of the heat exchanger element, which may be tubular or hollow, and having a relatively thin virgin wall. Such securement is with one of the lateral edges of the rib or fin being in contact with the exterior surface of the element or tube It and extending at a substantial angle therefrom. In Figs. 5, 6, and 7 the end rib or flu Il is so secured and so projects with one of its narrow edges in contact with the surface of the element or tube It. In Figs. 8, 9, and the end rib Ila of Fig. 4 is thus secured to and so projects from the exterior surface of the element or tube I6 with one of its short sides in contact with the element or tube It. In Figs. 15 and 16 the end rib or fin Ilb of the row of such ribs or fins shown in Figs. 14 and i5 is so attached to and thus projects from the element tube Ii. The row of ribs or fins Ilb indicated in Fig. 14 has its end rib or fin Ilb so secured to the element or tube ll with the flat portion II thereof in contact with the surface of the element or tube Ii. The row or helical coil of the ribs or fins formed according to either, ll, Ila, or Ilb, whose end rib or fin as aforesaid is secured to the elementor tube II is placed undersome longitudinal stress to cause the desired separation between the respective ribs or fins comprising such row. While subiected to such stress such row is either wound in the form of a ring about the element or tube I6 as indicated in Figs. 5 and 8 or in a helix thereabout as indicated in Figs. 7, 10, and 15, with at least the finally applied end of said row secured to the element or tube I6. Said longitudinal stress is maintained in the wound, coiled, and secured row of ribs or fins and causes a firm spring grip to be maintained by the edge of each of the ribs or fins in contact with the surface of the element or tube I6. This grip, maintained by said securement at least at the opposite ends of the applied row of such ribs or fins, affords a firm and efficient heat or cold exchanging contact between the element or tube I6 and each of the ribs or fins comprising the row of such ribs or fins applied to the element or tube. This gripping contact also affords substantial rigidity and stability to each of the several ribs or fins comprising the row thereof. Instead of being wound in a ring or helically about the element or tube I6, the row or rows of such ribs or fins may be disposed in any desired direction along and in contact with the surface of the element or tube I6 with at least its opposite ends secured thereto and maintaining throughout the row, said longitudinal tension with its attendant gripping action with an edge of such rib or fin in efficient heat or cold exchanging contact with element or tubular body I6.

When the element I0 is a hollow body one fluid is adapted to-be passed along the interior thereof while a usually different fluid is passed along the exterior thereof. The heat or cold exchanging from one of said fluids to the other occurs through the medium of said ribs or fins and the wall of the body ll. When the flow of the fluid subjected to the exterior surface of the body Ii has a flow longitudinally of the body I6, such fiowage causes the passage of such fluid between the component ribs or fins comprising each row thereof as well as through the open centers of each such rib or fin and the spaces between each row of such ribs or fins. When such flow is transverse to the body I6, such flowing medium fiows around all of the lateral surfaces of and through the central opening in each of the ribs or fins. Even when there be no substantial fiow of such fluid in any definite direction, the fluid is in. contact with all surfaces of each of the ribs or fins. Thus, under all conditions, there is a substantial rate of heat exchange to or from the fiuid and the fins as well as to and from the fiuid and the exposed surface of the body I8, and to or from the body I8 and the portions of the ribs or fins in contact therewith. This affords a very high rate of heat or cold exchange as well as a very strong light-weight, durable, and cheap structure.

The material of which the ribs or fins are formed is preferably cold rolled or cold drawn. This increases the surface density of such material, which increases its rate or heat or cold exchange. The shearing from tube III of the ribs or fins ll also increases the density of the metal at the cut surfaces, which likewise increases the rate of heat or cold exchange.

Those skilled in the art will readily understand from the foregoing, and be able to practice, the method of production of this heat or cold exchanging structural element as well as to practice the method by hand or by a number of substantially different apparatus with or without substantial change in such apparatus.

Lightness as well as cheapness of construction of a durable and highly eilicient heat or cold exchanging element is of great advantage and importance in this art. It will be understood that all of said advantages, among others, are retained by the herein disclosed heat orcold exchanging element, and that said structure may be readily and conveniently applied to any contour of the body It, as well as that when the body ii, for instance, has a tube, rod, or bar, the same may be readily bent as may be desired after the ribs or fins have been applied and secured thereto. It will also be understood that the heat or cold exchanging" mechanism will comprise any desired number and form body portions l6 provided with the ribs or fins and suitably mounted upon header walls or otherwise.

The invention disclosed herein may be manufactured and used by or for the Government of the-United States of America for governmental purposes without the payment of any royalties thereon or therefor.

Having now so fully described our invention that others skilled in the art may therefrom make and use the same, what we claim is:

1. The method of making a heat exchange fin comprising partially cutting a longitudinally apertured bar of high heat conductivity metal alternately and successively from opposite sides, the several cuttings being made with a substantially uniform spacing and in a direction transversely to the length of the bar to directly form by the cutting operation an apertured heat exchange fin of substantially uniform thickness throughout for securement to a heat exchange element.

2. The method of making a heat exchange device including a heat exchange element provided with a heat exchange fin secured thereto, comprising partially cutting a bar of high heat conductivity metal alternately and successively from opposite sides without wastage of material and in a direction transversely of its length to directly form by the cutting operation a heat exchange fin, the cutting in each of said cutting operations proceeding from one side of the bar and extending progressively to a point short of the opposite side thereof, disposing the fin so formed under a longitudinal stress about a heat exchange element, and securing the fin while in the stressed condition to the said heat exchange element.

3. The method of making a heat exchange device including a heat exchange element provided with a heat exchange fin secured thereto, comprising partially cutting a longitudinally apertured bar of high heat conductivity metal alternately and successively from opposite sides, the several cuttings being made with a substantially uniform spacing and in a direction transversely to the length of the bar to directly form by the cutting operation an apertured heat exchange fin of substantially uniform thickness throughout, disposing the fin so formed with its exterior edge in contact with the surface of a heat exchange element, and securing, the mi in this position to the said element.

4. A row of cut heat exchange ribs of high heat conductivity metal adapted to be secured to a heat exchange element, comprising a plurality of integral ribs alternately diverging from opposite sides of the row in pairs, each of said ribs extending from one side of the row to the other and at opposite sides of the row being secured to adjacent ribs, the entire lateral surfaces of said ribs being formed by a cutting operation and cold worked thereby.

5. A heat exchange device comprising in combination a heat exchange element and a row of cut heat exchange ribs of high heat conductivity metal secured thereto, the ribs of said row being integral and alternately diverging from opposite sides thereof in pairs, each of said ribs extending from one side of the row to the other and at opposite sides of the row being secured to adjacent ribs, the entire lateral surfaces of said ribs being formed by a cutting operation and cold.

worked thereby.

6.- A heat exchange device comprising in combination a heat exchange element and a row of cut heat exchange ribs of high heat conductivity metal, the ribs of said row being integral and apertured and alternately diverging from opposite sides thereof in pairs, each of said ribs extending from one side of the row to the other and at opposite sides of the row being secured to adjacent ribs and the entire lateral surfaces of said ribs being formed by a cutting operation and cold worked thereby, the row of ribs being disposed with its exterior edge in contact with the surface of a heat exchange element and secured thereto.

ALFRED J. BERG. JOHN O. HUSE. 

